再次将指针传递给函数时遇到麻烦

Question

Trying to pass the root of my Binary Search Tree (BST) to the UI function (I need to pass it as a modifiable variable or however it's called)

main.cpp

cmd = UI.uiCmd()

BST<Matrix> *data = new BST<Matrix>;
Matrix mat;

UI.handle (cmd, mat, data); // passing command, class object, root of BST

The UI class in the header has:

private:
void handle (int, Matrix, BST<Matrix *>);

and in the .cpp file:

void ui::handle(int cmd, Matrix matrix, BST<Matrix *> data)

I know I'm messing up somewhere but I can't say where, I have a very poor grasp of pointers

The error I get: it thinks BST<Matrix>&* while function asks BST<Matrix> *

I don't plan on using C++ much for now, so a detailed answer (while appreciated) is not necessary.

Answer 1

Your function signature should look like

void handle (int, Matrix, BST<Matrix>*)

instead of

void handle (int, Matrix, BST<Matrix *>)

Answer 2

Firstly BST<Matrix *> is not the same as BST<Matrix>* . One is a container of pointers, the other is a pointer to a container.

Secondly, if you want to let the function modify an argument, you can pass it by reference:

void ui::handle(int cmd, sMat matrix, BST<sMat>& data) 

and call it like

cmd = UI.uiCmd() 

BST<Matrix> data;
Matrix mat; 

UI.handle(cmd, mat, data);

Answer 3

You have created

    BST<Matrix> *data = new BST<Matrix>;

but the function asked for a BST<Matrix*> argument. Note the subtle difference

    BST<Matrix> * IS NOT same as  BST<Matrix*>